Zero Visibilities

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Joined: Mon Jun 17, 2013 3:51 pm

Zero Visibilities

Postby stucky » Fri Jul 19, 2013 6:15 pm

I'm running simobserve simulations that are generating visibilities with a majority of elements in the DATA columns being zero for both real and imaginary parts. Here are the simobserve parameters for just one for the runs that are generating these zero values.

Code: Select all

taskname           = "simobserve"
project            =  "sweep0"
skymodel           =  "cmap.image"
inbright           =  "1mJy/pixel"
indirection        =  "J2000 21h36m30 47d25m48"
incell             =  "210.6arcsec"
incenter           =  "700MHz"
inwidth            =  "1MHz"
complist           =  ""
compwidth          =  "8GHz"
setpointings       =  False
ptgfile            =  "pointings/sweep0.ptg"
integration        =  "10s"
direction          =  ['']
mapsize            =  ['', '']
maptype            =  "hexagonal"
pointingspacing    =  ""
caldirection       =  ""
calflux            =  "1Jy"
obsmode            =  "int"
refdate            =  "2014/05/21"
hourangle          =  "00:00:00"
totaltime          =  "1"
antennalist        =  "array2.cfg"
sdantlist          =  ""
sdant              =  0
thermalnoise       =  ""
user_pwv           =  1.0
t_ground           =  270.0
t_sky              =  260.0
tau0               =  0.1
seed               =  11111
leakage            =  0.0
graphics           =  "both"
verbose            =  False
overwrite          =  True

I've been able to rule out several possibilities by adjusting these parameters. I feel fairly confident the problem does not lie with any of these parameters: hourangle, totaltime, antennalist, inbright, and the skymodel (changed it to a proto disk image from one of the VLA tutorials). The indirection parameter is set to the Zenith of my observatory. The .ptg files are setup to make the array stay fixed on zenith and take data as the 30deg x 30deg skymodel moves across the sky. The antenna array configuration file that's listed is just a simple 4 x 4 rectangular fictitious array that's placed in Mongolia.

A secondary problem that may or may not be related are the non-zero w values I'm getting. Which my advisor tells me should not be happening for brief snapshots of the sky such as this.

Any insight you can provide here will be greatly appreciated. Thanks.

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